Formation of Photo-Luminescent Patterns on Paper Using Nanocrystalline Quantum Dot Ink and Mist Deposition

This study explores patterned deposition of cadmium selenide (CdSe) nanocrystalline quantum dot (NQD) thin films on paper substrates using the process of mist deposition. Because NQDs film can be engineered to produce unique emissive response, an application that prompted this research is concerned with printing of security/anti-counterfeiting patterns and identification labels on various substrates, including paper. Among other thin-film techniques using colloidal solution as a precursor, mist deposition is in this study predicted through Monte Carlo simulation and demonstrated through experiments to be particularly suitable for creating NQD micro-patterns on paper. In this experiment, barcode-like patterned NQD films were successfully deposited on various types of paper substrates. The films were characterized for fluorescence intensity, emission spectrum and quality of pattern transfer from shadow mask to the deposited film. Time dependent degradation of the deposited pattern was among key aspects investigated. The results obtained indicate that NQD films deposited on paper and encapsulated using plastic laminate did not show degradation in photoluminescence intensity over a period of nine weeks.